Clip for carbon brushes

ABSTRACT

A clip for use with carbon brushes to form an assembly suitable to operate in electric equipment, the clip having at least two members, one of the members being provided with a resilient protruding segment. This segment moves to a position flush with the surface of the member to which it is secured while the clip is sliding into a groove in the carbon brush, and snaps back to its normal position when it engages a recess in the groove. With this construction, the clip is permanently secured to the brush.

United States Patent Inventor Appl. No.

Filed Patented Assignee Archie R. Kingsbury Taylors, S.C.

June 7, 1968 May 4, 1971 Union Carbide Corporation CLIP FOR CARBON BRUSHES 11 Claims, 7 Drawing Figs.

U.S. Cl

Int. Cl

Field of Search References Cited UNITED STATES PATENTS 2,295,444 9/1942 Woodward 2,520,379 8/1950 Ward 310/246 2,706,261 4/1955 Burchfield 310/246 FOREIGN PATENTS 1,035,208 4/1953 France 310/249 Primary Examiner-D. F. Duggan Assistant Examiner-R. Skudy Att0rneysPaul A. Rose, Robert C. Cummings, Frederick J.

McCarthy, Jr. and D. Laurence Padilla ABSTRACT: A clip for use with carbon brushes to form an assembly suitable to operate in electric equipment, the clip having at least two members, one of the members being provided with a resilient protruding segment. This segment moves to a position flush with the surface of the member to which it is secured while the clip is sliding into a groove in the carbon brush, and snaps back to its normal position when it engages a recess in the groove. With this construction, the clip is permanently secured to the brush.

PATENTED HAY 41971 NVENTOR KING CHIE ATTORNEY CLIP FOR CARBON BRUSHES FIELD OF INVENTION DESCRIPTION OF PRIOR ART A brush clip is a component which is attached to an electric brush of the type conventionally employed in certain electrical devices such as motors and generators. It is used to prevent wear at the top of the brush by accommodating the spring finger or hammer. It is consequently often referred to as a hammer or finger clip.

A wide variety of clip configurations are currently in use. In addition, several types of constructions are presently used to secure the clip to the brush. A typical clip configuration and connection is illustrated in Publication No. CBl-l96l published in Oct. 1961 by the National Electric Manufacturers Association and referred to therein as an A" clip. This assembly consists generally of a metal strip bent so as to lie on top of the brush and connected to the side of the brush by one or more rivets. This particular assembly generally includes a metal washer between the rivet head and the brush.

Several problems are often encountered in the production of this type of brush-clip assembly. Spinning the heads on the rivet in order to obtain a secure attachment is a delicate and difficult task even for the skilled artisan. In addition, breakage of the carbon or graphite brush sometimes occurs in the area of the rivet joint because the brush is weakened by the assembly manipulations.

US. Pat. No. 3,355,6I1 solves the aforementioned problems by providing a brush-clip assembly which does not depend upon a rivet or other fastener to secure the components together. The assembly includes a nonmetallic clip which is interlockingly secured to the brush in a groove at the side of the brush.

Other types of clips and brush-clip assemblies are disclosed in other US. patents. US. Pat. No. 1,490,307 for example, advocates a generally U-shaped metallic clip which is positioned into undercut notches in the sides of the brush and held in place by the spring tension on the clip itself. US. Pat. No. 3,017,529 discloses a clip or cap which is laminated, the lower lamination being made of neoprene or other rubber composition while the top layer material is a suitable material to prevent breakage in operation. The clip is secured to the top of the brush by being positioned in an angled dovetail slot placed in the top surface of the brush.

While the aforementioned configurations represent somewhat successful attempts to solve longstanding problems in an assembly of this type, there is still a need for an improved clip and/or assembly to effect optimum operating conditions. The present invention provides a novel clip for use in such an assembly, the clip being constructed such that it is easily and permanently secured to the brush.

DESCRIPTION OF THE INVENTION Broadly stated, the clip of the invention comprises two members secured together, one of the members having a protruding segment extending from a portion thereof. The protruding segment is designed so that it is positioned flush with and substantially parallel to the member of which it is a part in response to a pressure applied during installation on the brush and returns to its normal projecting position upon the release of pressure. As hereinafter explained, the protruding segment is, in the preferred embodiment, constructed of a resilient material which .will yield under the pressures applied in assembly and will springback" when pressure is relieved.

DESCRIPTION OF THE DRAWING The invention will be more readily understood by referring to the drawing, wherein:

FIG. 1 is an isometric view of a brush-clip assembly typical h w nysmi n V FIG. 2 illustrates a brush prior to the insertion of the clip of the invention, A V W A t FIG. 3 is a side view, partially in section, of a split-wafer brush positioned under the clip of the invention;

FIG. 4 is a front elevational view of a clip typical of the invention;

FIG. 6 is an illustration of another embodiment of the clip of the invention; and

FIG. 7 is an enlarged fragmentary view of the section.7 of FIG. 3.

Referring now to the drawing, there is shown in FIG. 1 a brush-clip assembly designated generally by the numeral 10. The assembly comprises a clip 12 and a brush 14. The clip 12 includes a first member 16 having a protruding segment 18 and a second member 20 substantially at a right angle relative to the first member 16. The member 16 resides in a groove 22 in the side of the brush while the member 20 extends across the top of the brush to provide a riding surface for the spring finger (not shown).

In FIG. 2, the groove 22 in brush 14 is more clearly illustrated. As there shown, a recess 24 is placed at about the center of the groove to accommodate the segment 18 of the clip. The groove is designed to retain the clip and is therefore shown as being dovetailed and is also preferably designed to provide a relatively close fit with the clip. With this construction, the pressure of the groove wall during assembly against the protruding segment causes the segment to recede to a position flush with the surface of the clip to which it is affixed while the clip is being pressed into the groove. As the clip slides past the recess 24, the protruding segment springs into the recess. The clip is then permanently locked into position. This is shown clearly in FIG. 3 and FIG. 7. A small tolerance between the top of the protruding segment and top of the recess may be permitted to enable a slight vertical movement of the clip during the operation of the assembly. A further cushioning effect to permit the assembly to absorb vibration can readily be accomplished by positioning a pad 26 between the clip 20 and the brushes as shown. The pad may be composed of any resilient material with appropriate thermal characteristics such as rubber, neoprene and nylon. FIG. 3 also illustrates that a plurality of brushes (i.e. brush 28) can be placed beneath the clip when required.

FIG. 4 depicts the clip 20 in a front elevation view while FIG. 5 shows the same clip in cross section. The member 20 normally forms an included angle A of about 45, 75 and with member 16 as shown. This angle could be varied to conform to the contour of the brush top or vary in accordance with the design of the particular clip configuration employed. The clip members are normally made an integral unit during the fabrication of the clip. However, any sturdy mechanical connection between members which can withstand the vibrational forces experienced during operation of the system is acceptable for the purposes of this invention.

In the preferred embodiment, the protruding segment must be composed of a material with sufficient resiliency to permit it to yield substantially the total amount of its projected distance and spring back to its original position. This projected distance is shown by the letter d in FIG. 5 and it will vary according to the size of clip employed. Normally, the degree of extension d is generally of a magnitude of about 0.040 inch. Materials which have displayed sufficient resiliency are polypropylene, nylon, plastics in general, fibre glass,

FIG. 5 is a sectional view view taken along lines 5-5 in FIG.

Teflon,* Nylafil, molded fibers, hard rubber or metals.

Examples of suitable metals are steel, steel alloys, aluminum in the most advantageous embodiment, an integral part of the clip. Of course, any means of attachment such as fusion bonding will suffice provided that the desired springback function of the segment is maintained and the segment is strong enough to permanently secure the clip to the brush. While the angle of projection of the protruding segment relative to the clip member of which it is a part is generally not critical, it has been observed that a stronger shock resistant unit is obtained if the segment forms an angle of about 5 with the longitudinal axis of the clip member as shown by the letter B in FIG. 5.

FIG. 6 displays another embodiment of the clip of the i nv ention. As shown in FIG. 6, the clip is in the form of a U configuration with members 30,32,34, all integrally formed together. The extended segment 36 is integrally secured to member 30 while segment 38 is similarly secured to member 34. A plurality of brushes can be placed between members 30,34 segments 36, 38 fitting into brush recesses in the outermost brushes during assembly.

The following is an example of a clip and brush-clip assembly typical of the invention.

EXAMPLE A clip similar to that shown in FIG. 5 composed entirely of Nylafil was molded into a single unit having the following dimensions: a first dovetailed member (No. 16 in FIG. 5) was 0.090 inch thick, 0.375 inch wide and 0.625 inch high as measured to the lower surface of the second member at the joint between members. A protruding segment extending a distance d of 1/32 inch was 0.042 inch thick and /6 inch wide. The top of the segment was positioned 0.230 inch from the aforementioned lower surface of the second member and the segment was substantially centered relative to the width of the first member. The second or top member formed an angle of 75 with the first member and projected a distance of 0.493 inch. This member was 0.060 inch thick and 0.375 inch wide.

The clip was placed in a dovetailed groove 0.375 inch wide by 0.625 inch long by 0.115 inch deep. The pressure exerted against the protruding segment by the groove wall when the clip was pressed into the groove caused the segment to seek a position flush with the surface of the first member. A recess was machined into the groove, the top of the recess being positioned 0.220 inch from the top of the brush.

A number of brush-clip assemblies of the type described in the example were tested for vibration and all withstood at least 15 million vibrations without loosening. The temperature of the clips was varied during the testing to simulate operating conditions. None of the clip assemblies failed in operation.

It will be appreciated that many modifications of the invention are possible. For example, the protruding segment can be affixed to the clip member by a hingeable securing means such as a pin and spring tension can be effected by a device such as a spring coil, leaf spring, cushion pad or the like positioned behind the segment. This type of construction is less desirable than the aforementioned preferred embodiment since it is more expensive to manufacture. Other modifications within the purview of this invention include different clip shapes such as a T clip; clip members which are laminated with suitable materials, particularly the top member; brush grooves which are enclosed on all sides such that a slot is formed in the top of surface of said first member when pressure is applied to said segment and returned to its orrgrna positron upon release of such pressure.

2. The clip of claim 1 wherein said members form an angle a of from about 45 to about therebetween.

3. The clip of claim 1 wherein said protruding segment is composed of a material selected from a group comprising nylon, Nylafil, plastic, fiberglass and resilient metals.

4. The clip of claim 1 wherein the projected distance of said segment is about 0.040 inch.

5. The clip of claim 1 wherein a third member is affixed to said second member substantially parallel to said first member such that said clip is substantially U shaped.

6. The clip of claim 3 wherein said segment and said members are an integral unit and are composed of a material selected from a group comprising nylon, Nylafil, plastic, fiberglass and resilient metals.

7. A clip for use in an electric brush assembly comprising:

a. a first member, said member having a protruding segment extending therefrom and having a cross-sectional area designed for sliding into a member having a mating female groove so that said first member can be retained therein;

b. means for springing said protruding segment into a position substantially flush with the surface of said first member when pressure is applied to said segment and for releasing said segment when pressure is removed therefrom; and

c. a second member secured to said first member, said member forming an angle of from about 45 to 90 therebetween.

8. A brush-clip assembly comprising:

a. a clip having a least two members, said members being secured together and forming an angle of between about 45 and about 90 therebetween, at least one of said members having a protruding segment extending therefrom, having means to move said segment substantially flush with the surface of said segment substantially flush with the surface of said member when pressure is applied to said segment and to release said segment when pressure is removed, and having a cross-sectional area designed for sliding into a mating groove in a brush so that said member can be retained therein; and

b. a carbonaceous brush, said brush having a groove in at least one sidewall thereof for receiving the member having said protruding segment, and having a recess in said sidewall within said groove so that when said clip member is positioned into said groove, the protruding segment will project into said recess and firmly secure the clip to said brush.

9. The assembly of claim 8 wherein said clip and said groove are dovetailed.

10. The assembly of claim 8 wherein said clip members and said protruding segment are integral and are composed of a material selected from the group comprising nylon, plastic, fibre glass, Nylafil and resilient metals.

11. The assembly of claim 8 wherein a resilient pad is placed at the top ofsaid brush and beneath said clip member to stabilize said assembly against vibration during operation. 

1. A clip for use in an electric brush assembly comprising first and second members secured together and a protruding segment affixed to said first member, said first member having a crosssectional area designed for sliding into a brush member having a mating female groove so that said first clip member can be retained therein, and said segment affixed to said first member being constructed of a resilient material such that it recedes to a position substantially flush with the surface of said first member when pressure is applied to said segment and returned to its original position upon release of such pressure.
 2. The clip of claim 1 wherein said members form an angle of from about 45* to about 90* therebetween.
 3. The clip of claim 1 wherein said protruding segment is composed of a material selected from a group comprising nylon, Nylafil, plastic, fiberglass and resilient metals.
 4. The clip of claim 1 wherein the projected distance of said segment is about 0.040 inch.
 5. The clip of claim 1 wherein a third member is affixed to said second member substantially parallel to said first member such that said clip is substantially U shaped.
 6. The clip of claim 3 wherein said segment and said members are an integral unit and are composed of a material selected from a group comprising nylon, Nylafil, plastic, fiberglass and resilient metals.
 7. A clip for use in an electric brush assembly comprising: a. a first member, said member having a protruding segment extending therefrom and having a cross-sectional area designed for sliding into a member having a mating female groove so that said first member can be retained therein; b. means for springing said protruding segment into a position substantially flush with the surface of said first member when pressure is applied to said segment and for releasing said segment when pressure is removed therefrom; and c. a second member secured to said first member, said member forming an angle of from about 45* to 90* therebetween.
 8. A brush-clip assembly comprising: a. a clip having a least two members, said members being secured together and forming an angle of between about 45* and about 90* therebetween, at least one of said members having a protruding segment extending therefrom, having means to move said segment substantially flush with the surface of said segment substantially flush with the surface of said member when pressure is applied to said segment and to release said segment when pressure is removed, and having a cross-sectional area designed for sliding into a mating groove in a brush so that said member can be retained therein; and b. a carbonaceous brush, said brush having a groove in at least one sidewall thereof for receivinG the member having said protruding segment, and having a recess in said sidewall within said groove so that when said clip member is positioned into said groove, the protruding segment will project into said recess and firmly secure the clip to said brush.
 9. The assembly of claim 8 wherein said clip and said groove are dovetailed.
 10. The assembly of claim 8 wherein said clip members and said protruding segment are integral and are composed of a material selected from the group comprising nylon, plastic, fibre glass, Nylafil and resilient metals.
 11. The assembly of claim 8 wherein a resilient pad is placed at the top of said brush and beneath said clip member to stabilize said assembly against vibration during operation. 